name: SMTP2GO API Rate Limits
description: Rate limiting rules for the SMTP2GO REST API covering per-endpoint throttles,
  account-level sending limits, and error handling guidance.
version: '0.2'
url: https://developers.smtp2go.com/docs/rate-limiting
generated: '2026-08-13'
method: searched
source: https://developers.smtp2go.com/docs/rate-limiting
sources:
  - https://developers.smtp2go.com/docs/rate-limiting
  - openapi/_original/smtp2go-openapi-original.yml
limit_count: 8
response_headers:
  published: []
  note: >-
    SMTP2GO publishes NO rate-limit response headers. There is no RateLimit-*,
    no X-RateLimit-*, no Retry-After, and none is declared on any of the 73
    operations in the provider's OpenAPI. A client learns it is throttled only
    from the 429 status and must implement its own backoff — there is no runtime
    budget signal to read.
  status_on_exhaustion: 429
limits:
  - scope: endpoint
    endpoint: /v3/activity/search
    operation_id: search-activity
    limit: 60
    period: minute
    http_status_on_violation: 429
    description: The activity search endpoint is limited to 60 requests per minute.
    source: https://developers.smtp2go.com/docs/rate-limiting
  - scope: endpoint
    endpoint: /v3/api_keys/add
    operation_id: add-api-key
    limit: 5
    period: minute
    http_status_on_violation: 429
    description: Creating new API keys is limited to 5 requests per minute.
    source: 'openapi/_original/smtp2go-openapi-original.yml — operation description'
  - scope: endpoint
    endpoint: /v3/subaccount/add
    operation_id: add-subaccount
    limit: 50
    period: hour
    http_status_on_violation: 429
    description: Adding subaccounts is rate limited to 50 calls per hour.
    source: 'openapi/_original/smtp2go-openapi-original.yml — operation description'
    correction: >-
      A previous round of this file recorded "/v3/subaccounts/add, 10 per hour".
      Both the path and the number were wrong; the provider's own contract states
      50 calls per hour on /subaccount/add.
  - scope: ip
    limit: unspecified
    period: unspecified
    http_status_on_violation: 429
    description: >-
      An IP issuing what SMTP2GO deems too many requests, or too many error
      responses, is timed out for an indeterminate period of no less than one
      minute. The threshold is not published.
    source: https://developers.smtp2go.com/docs/rate-limiting
  - scope: api_key
    limit: configurable
    period: configurable
    default: unlimited
    http_status_on_violation: 429
    description: >-
      Per-API-key sending rate limits are set individually under Sending > API
      Keys in the SMTP2GO app and default to unlimited. Exceeding the configured
      limit produces an "API key ratelimit exceeded" error and notifies team
      members who have notifications enabled. The same per-credential limit
      exists on SMTP users (default_ratelimit_value / default_ratelimit_period
      are returned by /api_keys and /users/smtp).
    source: https://developers.smtp2go.com/docs/rate-limiting
  - scope: account
    limit: 1000
    period: day
    description: >-
      New paid accounts carry a temporary initial quota of 1,000 emails per day
      during a one-time review. Mail over that limit is held in the queue and
      released on full activation, rather than rejected.
    source: https://developers.smtp2go.com/docs/rate-limiting
  - scope: plan
    plan: Free
    limit: 1000
    period: month
    description: The free plan is capped at 1,000 emails per month.
    source: https://developers.smtp2go.com/docs/rate-limiting
  - scope: plan
    plan: Free
    limit: 200
    period: day
    description: The free plan is limited to 200 emails per day.
    source: https://developers.smtp2go.com/docs/rate-limiting
  - scope: plan
    plan: Free
    limit: 25
    period: hour
    description: >-
      The free plan is additionally limited to 25 emails per hour if no sender
      domain is verified; verifying a sender domain removes the hourly cap.
    source: https://developers.smtp2go.com/docs/rate-limiting
payload_limits:
  - {scope: request body, limit_mb: 1, applies_to: all non-email endpoints, since: '2026-06-11'}
  - {scope: request body, limit_mb: 50, applies_to: /v3/email* endpoints, since: '2026-06-11'}
  - {scope: message, limit_mb: 50, applies_to: 'total email size including content, attachments and headers'}
  - {scope: recipients, limit: 100, applies_to: 'each of To, CC and BCC per message'}
  - {scope: recipients, limit: 100, applies_to: destination numbers per /sms/send call}
  - {scope: queue, limit: 10000, applies_to: scheduled emails queued at one time}
error_handling:
  too_many_requests:
    http_status: 429
    message: Too Many Requests
    description: >-
      Returned when an IP address is timed out due to excessive requests or error
      responses. The timeout lasts no less than 1 minute.
  api_key_ratelimit_exceeded:
    description: >-
      Returned when a per-API-key sending rate limit configured in the app is
      exceeded. An email notification is sent to team members with notifications
      enabled.
backoff_guidance: >-
  Pause and progressively lower the request rate until 200 OK responses return.
  Also ensure the requests being sent are succeeding — a high error rate itself
  triggers the IP timeout. Do not retry immediately; there is no Retry-After to
  honour, so use exponential backoff.